• Korean Journal of Optics and Photonics
• /
• v.24 no.3
• /
• pp.135-142
• /
• 2013

Two white light emitting diodes(LEDs) were fabricated by using two kinds of yellow phosphor, YAG:Ce and $(Sr,Ba)_2SiO4:Eu$, and their spectroscopic properties were analyzed as a function of temperature from room temperature to $80^{\circ}C$. The asymmetric double sigmoidal function was applied to both blue and yellow peaks of the emitting spectrum to obtain the center wavelength, the amplitude, the half width, and the skewness parameters. According to this analysis, the center wavelength of the blue peak shifted to longer wavelength while that of the yellow peak shifted to shorter wavelength. In addition, some of the skewness parameters were found to increase upon heating, which indicates that spectrum asymmetry becomes enhanced at higher temperatures. The changes in the color coordinates and the luminous efficacy were larger for the case of silicate-based white LED. These results suggest that the silicate-based white LED is inferior to the YAG-based white LED from the viewpoint of color stability, efficacy and color rendering index.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.9
• /
• pp.812-817
• /
• 2016

This paper dealt with electrical and optical requirements of naval vessel's LED luminaires. And the products have been tested to determine whether the products meet these requirements or not. This study analyzes the cost-effectiveness of the LED luminaires which have been implemented for the application to naval vessel since 2012. The LED requirements were proposed based on comparison among other standards/specifications such as Korean Industrial Standard(KS), Korean Defense Specification(KDS) and US Navy Military Specification(MIL). Application of the proposed requirements were then be verified by analyzing and testing the electrical and optical characteristics of both fluorescent Luminaires and LED luminaires, and the LED luminaires were installed to A1 naval vessels according to the proposed requirements. As results, approximately 40% of power consumption was saved by using LED luminaires compared to using fluorescent luminaires while luminous flux was increased by 10~15%. Moreover, using LED luminaires of the proposed requirements exhibited the effect of reducing approximately 4,900 fluorescent luminaires in 10 naval vessels in the time period between 2012 to 2015, which is equivalent to cost reduction of \0.56M approximately. Such cost reduction is further expected considering the LED luminaires will continue to be applied to naval vessels in the future.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.44 no.12
• /
• pp.12-17
• /
• 2007

The effects of the evaporation rate of MgO films using an electron beam on the MgO properties and the discharge characteristics of a plasma display panel(PDP) were investigated and analyzed. Mgo films were deposited with the various MgO evaporation rates. The MgO properties such as the crystal orientation, the surface roughness, and the film structure, were inspected using XRD(X-ray diffractometry), AFM(atomic force microscopy). From the experiments and Paschen law, the maximum value of the secondary, electron emission coefficient $(\gamma)$ was obtained at the evaporation rate of $5\AA/sec$. The minimum firing voltage and the maximum luminous efficiency were obtained at an evaporation rate of $5\AA/sec$. In the MgO film deposited at $5\AA/sec$, the (200) orientation and $F^+$ center were most intensive. The XRD results and cathode-luminescence(CL) spectra show the $\gamma$ values are correlated with $F/F^+$ centers of the molecular structure of MgO films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.9
• /
• pp.577-582
• /
• 2017

The white light of a hybrid LED is obtained by using red and green organic fluorescent layers made of polymethylmethacrylate (PMMA) films, which function as color down-conversion layers of blue light-emitting diodes. In this research, we studied the fluorescence properties of a red organic fluorophore, employing perylene bisimide derivatives applicable to hybrid LEDs. The solubility, thermal stability, and luminous efficiency are important characteristics of organic fluorophores for use in hybrid LEDs. The perylene fluorescent compounds (1A and 1B) were prepared by the reaction of 4-bromophenol and 4-iodophenol with N,N'-bis(4-bromo-2,6-diisopropylphenyl)-1, 6,7,12-tetrachloroperylene-3,4,9,10-tetracarboxyl diimide (1) in the presence of dimethyl formaldehyde (DMF) at $70^{\circ}C$. The synthesized derivatives were characterized by using $^1H-NMR$, FT-IR, UV/Vis absorption and PL spectra, and TGA analysis. Compounds 1A and 1B showed absorption and emission at 570 nm and 604 nm in the UV/Vis spectrum. We also documented favorable solubility and thermal stability characteristics of the perylene fluorophores in our work. Perylene fluorophore 1, with the 4-bromophenol substituent 1A, exhibited particularly good thermal stability and solubility in organic solvents.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.1
• /
• pp.45-55
• /
• 2010

Recently a number of media facade buildings making beautiful cityscape landmark has been increased in Seoul. However, indiscreet adaptation of media facade cause problems such as light pollution and poor city image. This paper was to investigate luminous characteristics of media facade building. Five representative media facade buildings in Seoul have been selected. The CS-100 and ProMetric-1400 were used to measure the luminance and color temperature of the facades. The measurement points were located at the opposite spot of the building. The results showed that maximum media facade luminance of such buildings exceed Seoul design guideline. Also, color temperature with over 5,500[K] that exceed the design guideline were mostly used in all the facades.

• Journal of Advanced Navigation Technology
• /
• v.15 no.6
• /
• pp.1111-1117
• /
• 2011

We was designed the portable LED light which can shadowless shooting and developed using a high-power LED that medical attention as a new lighting components for structural confirmation of oral dental area, medical and surgical lesions in the local area. LED which applied to the development, was used the 3-color LEDs for possible of implement a variety of colors and adjusted the light intensity. It is being magnified of delicacy expressiveness and three-dimensional for tone of the subject-specific. It has been developed a highly efficient light module that LED is used to consider the electrical characteristics and optical properties. SMPS has We was designed the portable LED light which can shadowless shooting and developed using a high-power LED that medical attention as a new lighting components for structural confirmation of oral dental area, medical and surgical lesions in the local area. LED which applied to the development, was used the 3-color LEDs for possible of implement a variety of colors and adjusted the light intensity. It is being magnified of delicacy expressiveness and three-dimensional for tone of the subject-specific. It has been developed a highly efficient light module that LED is used to consider the electrical characteristics and optical properties. SMPS has produced for use in mobile that can be driven at low voltage. In addition, it was also possible to implement a variety of colors from monochromatic Light to polychromatic light using by PWM control method and were available 32,768.

• Journal of the Korean Home Economics Association
• /
• v.41 no.8
• /
• pp.33-53
• /
• 2003

A Study on the color comparison of Korean Saek-dong and Italian futurist fashion It is generally recognized that the color scheme and its characteristics as a product of living culture are strongly reflected in clothing. This study concentrates on the color comparison of Korean Saek-dong which has been used in traditional Korean clothing and Italian futurist fashion which showed dynamic characteristics and brilliant colors. The purpose of this study is to investigate the external format, emotions, functions and meanings of the colors in Korean Saek-dong and Futurist fashion, and to find similarities and differences between them. The results of the study are as follows. The similarities between them are harmony of vivid colors like a rainbow, no-use of black color and expression of rhythm through repeated geometrical shapes. They have been used as festive costumes and have implied meaning of happiness and pleasure. The differences, in the external formats, are as follows. Korean Saek-dong has striped patterns including the color white, and has regular distances among the stripes. But, Futurist fashion includes luminous or fluorescent colors and metallic colors. In addition, it has repeated motifs of geometrical shapes and geometrically divided areas. While Saek-dong expresses Sangsaeng through the conceptual use of color, Futurist fashion shows simultaneity, speed and dynamics through spiritual functions of crossing and inter-penetration. In emotional aspect, Saek-dong expresses pleasure of children's mind and Futurist fashion expresses pleasure of city. In functional aspect, Saek-dons expresses a concept of ceremonial beauty, which is spiritual and symbolizes good auspices, holiness and sorcery. So it is used for ceremonial costume. But, Futurist fashion reflects the harmony of colors created from modem and urban images and shows the willingness and emotion of solving futuristic avant-garde, modernity, dynamics, transformation and bellicosity. So it is used for daywear. While Saek-dong represents succession of tradition, Futurist fashion represents resistance of tradition in cultural aspects.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.1
• /
• pp.29-35
• /
• 2000

Luminescent characteristics of SrS:Cu,X TFeL devices fabricated by electron-beam deposition system were studied. The SrS powders were used as the host materials and Cu, $CuF_2,\;Cu_2S$ or CuCl powders were added as the luminescent center. The emission spectra of the SrS:Cu,X TFEL devices strongly depended on coactivators. The luminance($L_{40}$) and efficiency(${\eta}_{20}$) of SrS:$Cu_2S$ TFEL device were 1443 cd/$m^2$ and 2.44 lm/w, respectively. Green color was observed from this TFEL device. The luminous efficiency of SrS:$Cu_2S$ TFEL device was higher than that of ZnS:Tb TFEL device, and it also could be good green phosphors for TFEL devices. The luminance($L_{40}$) and efficiency(${\eta}_{20}$) of SrS:CuCl TFEL device were 262 cd/$m^2$ and 0.26 lm/w, respectively. Blue color was emitted from this TFEL device.

• Culinary science and hospitality research
• /
• v.16 no.3
• /
• pp.250-258
• /
• 2010

This study was performed to find the most desirable mixing formula for Sulgidduk added with Cheongkukjang powder for various benefits. The optimal mixing formulas were identified by evaluations of ingredients, the color, and the sensory and textual characteristics. As the amount of Cheongkukjang powder increased, the rice cake appeared redder, yellower and less luminous. The amount of crude ash was significantly smaller in the experimental groups than in the control group, and the amount of crude protein and crude fat was significantly high. The change in texture according to the amount of Cheongkukjang powder was not statistically significant, but hardness, adhesiveness, and cohesiveness showed significant differences(p<0.05). It was also found that chewiness increased while adhesiveness decreased as storage time increased. According to the results of the sensory evaluation, scores in the color and aroma decreased as the amount of Cheongkukjang powder increased. Overall acceptability score was highest in the 5% group, consisting of 68% of rice powder, 5% of Cheongkukjang powder, 10% of sugar, and 17% of water.

• Journal of the Korean Vacuum Society
• /
• v.16 no.5
• /
• pp.338-342
• /
• 2007

The magnesium oxide (MgO) protective layer plays an important role in plasma display panels (PDPs). In this paper, we describe the structural and discharge properties of MgO thin films, which were prepared by the ion-beam-assisted deposition (IBAD) of oxygen as the protective layer of PDPs. The energy of the oxygen ion beam was used as the parameter to control the deposition. We found that the oxygen ion beam energy was effective in determining in structural and discharge characteristics. The lowest firing inception voltage, the highest brightness and the highest luminous efficiency were obtained when the MgO thin film was deposited with an oxygen ion beam energy of 300 eV. The crystallization of the MgO thin film was also measured by X-ray diffraction analysis, and the surface quality was measured by atomic force microscopy.